i2c: Set a default timeout value for all adapters
[linux-2.6.git] / drivers / i2c / algos / i2c-algo-bit.c
1 /* -------------------------------------------------------------------------
2  * i2c-algo-bit.c i2c driver algorithms for bit-shift adapters
3  * -------------------------------------------------------------------------
4  *   Copyright (C) 1995-2000 Simon G. Vogl
5
6     This program is free software; you can redistribute it and/or modify
7     it under the terms of the GNU General Public License as published by
8     the Free Software Foundation; either version 2 of the License, or
9     (at your option) any later version.
10
11     This program is distributed in the hope that it will be useful,
12     but WITHOUT ANY WARRANTY; without even the implied warranty of
13     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
14     GNU General Public License for more details.
15
16     You should have received a copy of the GNU General Public License
17     along with this program; if not, write to the Free Software
18     Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
19  * ------------------------------------------------------------------------- */
20
21 /* With some changes from Frodo Looijaard <frodol@dds.nl>, Kyösti Mälkki
22    <kmalkki@cc.hut.fi> and Jean Delvare <khali@linux-fr.org> */
23
24 #include <linux/kernel.h>
25 #include <linux/module.h>
26 #include <linux/delay.h>
27 #include <linux/slab.h>
28 #include <linux/init.h>
29 #include <linux/errno.h>
30 #include <linux/sched.h>
31 #include <linux/i2c.h>
32 #include <linux/i2c-algo-bit.h>
33
34
35 /* ----- global defines ----------------------------------------------- */
36
37 #ifdef DEBUG
38 #define bit_dbg(level, dev, format, args...) \
39         do { \
40                 if (i2c_debug >= level) \
41                         dev_dbg(dev, format, ##args); \
42         } while (0)
43 #else
44 #define bit_dbg(level, dev, format, args...) \
45         do {} while (0)
46 #endif /* DEBUG */
47
48 /* ----- global variables --------------------------------------------- */
49
50 static int bit_test;    /* see if the line-setting functions work       */
51 module_param(bit_test, bool, 0);
52 MODULE_PARM_DESC(bit_test, "Test the lines of the bus to see if it is stuck");
53
54 #ifdef DEBUG
55 static int i2c_debug = 1;
56 module_param(i2c_debug, int, S_IRUGO | S_IWUSR);
57 MODULE_PARM_DESC(i2c_debug,
58                  "debug level - 0 off; 1 normal; 2 verbose; 3 very verbose");
59 #endif
60
61 /* --- setting states on the bus with the right timing: --------------- */
62
63 #define setsda(adap, val)       adap->setsda(adap->data, val)
64 #define setscl(adap, val)       adap->setscl(adap->data, val)
65 #define getsda(adap)            adap->getsda(adap->data)
66 #define getscl(adap)            adap->getscl(adap->data)
67
68 static inline void sdalo(struct i2c_algo_bit_data *adap)
69 {
70         setsda(adap, 0);
71         udelay((adap->udelay + 1) / 2);
72 }
73
74 static inline void sdahi(struct i2c_algo_bit_data *adap)
75 {
76         setsda(adap, 1);
77         udelay((adap->udelay + 1) / 2);
78 }
79
80 static inline void scllo(struct i2c_algo_bit_data *adap)
81 {
82         setscl(adap, 0);
83         udelay(adap->udelay / 2);
84 }
85
86 /*
87  * Raise scl line, and do checking for delays. This is necessary for slower
88  * devices.
89  */
90 static int sclhi(struct i2c_algo_bit_data *adap)
91 {
92         unsigned long start;
93
94         setscl(adap, 1);
95
96         /* Not all adapters have scl sense line... */
97         if (!adap->getscl)
98                 goto done;
99
100         start = jiffies;
101         while (!getscl(adap)) {
102                 /* This hw knows how to read the clock line, so we wait
103                  * until it actually gets high.  This is safer as some
104                  * chips may hold it low ("clock stretching") while they
105                  * are processing data internally.
106                  */
107                 if (time_after_eq(jiffies, start + adap->timeout))
108                         return -ETIMEDOUT;
109                 cond_resched();
110         }
111 #ifdef DEBUG
112         if (jiffies != start && i2c_debug >= 3)
113                 pr_debug("i2c-algo-bit: needed %ld jiffies for SCL to go "
114                          "high\n", jiffies - start);
115 #endif
116
117 done:
118         udelay(adap->udelay);
119         return 0;
120 }
121
122
123 /* --- other auxiliary functions -------------------------------------- */
124 static void i2c_start(struct i2c_algo_bit_data *adap)
125 {
126         /* assert: scl, sda are high */
127         setsda(adap, 0);
128         udelay(adap->udelay);
129         scllo(adap);
130 }
131
132 static void i2c_repstart(struct i2c_algo_bit_data *adap)
133 {
134         /* assert: scl is low */
135         sdahi(adap);
136         sclhi(adap);
137         setsda(adap, 0);
138         udelay(adap->udelay);
139         scllo(adap);
140 }
141
142
143 static void i2c_stop(struct i2c_algo_bit_data *adap)
144 {
145         /* assert: scl is low */
146         sdalo(adap);
147         sclhi(adap);
148         setsda(adap, 1);
149         udelay(adap->udelay);
150 }
151
152
153
154 /* send a byte without start cond., look for arbitration,
155    check ackn. from slave */
156 /* returns:
157  * 1 if the device acknowledged
158  * 0 if the device did not ack
159  * -ETIMEDOUT if an error occurred (while raising the scl line)
160  */
161 static int i2c_outb(struct i2c_adapter *i2c_adap, unsigned char c)
162 {
163         int i;
164         int sb;
165         int ack;
166         struct i2c_algo_bit_data *adap = i2c_adap->algo_data;
167
168         /* assert: scl is low */
169         for (i = 7; i >= 0; i--) {
170                 sb = (c >> i) & 1;
171                 setsda(adap, sb);
172                 udelay((adap->udelay + 1) / 2);
173                 if (sclhi(adap) < 0) { /* timed out */
174                         bit_dbg(1, &i2c_adap->dev, "i2c_outb: 0x%02x, "
175                                 "timeout at bit #%d\n", (int)c, i);
176                         return -ETIMEDOUT;
177                 }
178                 /* FIXME do arbitration here:
179                  * if (sb && !getsda(adap)) -> ouch! Get out of here.
180                  *
181                  * Report a unique code, so higher level code can retry
182                  * the whole (combined) message and *NOT* issue STOP.
183                  */
184                 scllo(adap);
185         }
186         sdahi(adap);
187         if (sclhi(adap) < 0) { /* timeout */
188                 bit_dbg(1, &i2c_adap->dev, "i2c_outb: 0x%02x, "
189                         "timeout at ack\n", (int)c);
190                 return -ETIMEDOUT;
191         }
192
193         /* read ack: SDA should be pulled down by slave, or it may
194          * NAK (usually to report problems with the data we wrote).
195          */
196         ack = !getsda(adap);    /* ack: sda is pulled low -> success */
197         bit_dbg(2, &i2c_adap->dev, "i2c_outb: 0x%02x %s\n", (int)c,
198                 ack ? "A" : "NA");
199
200         scllo(adap);
201         return ack;
202         /* assert: scl is low (sda undef) */
203 }
204
205
206 static int i2c_inb(struct i2c_adapter *i2c_adap)
207 {
208         /* read byte via i2c port, without start/stop sequence  */
209         /* acknowledge is sent in i2c_read.                     */
210         int i;
211         unsigned char indata = 0;
212         struct i2c_algo_bit_data *adap = i2c_adap->algo_data;
213
214         /* assert: scl is low */
215         sdahi(adap);
216         for (i = 0; i < 8; i++) {
217                 if (sclhi(adap) < 0) { /* timeout */
218                         bit_dbg(1, &i2c_adap->dev, "i2c_inb: timeout at bit "
219                                 "#%d\n", 7 - i);
220                         return -ETIMEDOUT;
221                 }
222                 indata *= 2;
223                 if (getsda(adap))
224                         indata |= 0x01;
225                 setscl(adap, 0);
226                 udelay(i == 7 ? adap->udelay / 2 : adap->udelay);
227         }
228         /* assert: scl is low */
229         return indata;
230 }
231
232 /*
233  * Sanity check for the adapter hardware - check the reaction of
234  * the bus lines only if it seems to be idle.
235  */
236 static int test_bus(struct i2c_algo_bit_data *adap, char *name)
237 {
238         int scl, sda;
239
240         if (adap->getscl == NULL)
241                 pr_info("%s: Testing SDA only, SCL is not readable\n", name);
242
243         sda = getsda(adap);
244         scl = (adap->getscl == NULL) ? 1 : getscl(adap);
245         if (!scl || !sda) {
246                 printk(KERN_WARNING "%s: bus seems to be busy\n", name);
247                 goto bailout;
248         }
249
250         sdalo(adap);
251         sda = getsda(adap);
252         scl = (adap->getscl == NULL) ? 1 : getscl(adap);
253         if (sda) {
254                 printk(KERN_WARNING "%s: SDA stuck high!\n", name);
255                 goto bailout;
256         }
257         if (!scl) {
258                 printk(KERN_WARNING "%s: SCL unexpected low "
259                        "while pulling SDA low!\n", name);
260                 goto bailout;
261         }
262
263         sdahi(adap);
264         sda = getsda(adap);
265         scl = (adap->getscl == NULL) ? 1 : getscl(adap);
266         if (!sda) {
267                 printk(KERN_WARNING "%s: SDA stuck low!\n", name);
268                 goto bailout;
269         }
270         if (!scl) {
271                 printk(KERN_WARNING "%s: SCL unexpected low "
272                        "while pulling SDA high!\n", name);
273                 goto bailout;
274         }
275
276         scllo(adap);
277         sda = getsda(adap);
278         scl = (adap->getscl == NULL) ? 0 : getscl(adap);
279         if (scl) {
280                 printk(KERN_WARNING "%s: SCL stuck high!\n", name);
281                 goto bailout;
282         }
283         if (!sda) {
284                 printk(KERN_WARNING "%s: SDA unexpected low "
285                        "while pulling SCL low!\n", name);
286                 goto bailout;
287         }
288
289         sclhi(adap);
290         sda = getsda(adap);
291         scl = (adap->getscl == NULL) ? 1 : getscl(adap);
292         if (!scl) {
293                 printk(KERN_WARNING "%s: SCL stuck low!\n", name);
294                 goto bailout;
295         }
296         if (!sda) {
297                 printk(KERN_WARNING "%s: SDA unexpected low "
298                        "while pulling SCL high!\n", name);
299                 goto bailout;
300         }
301         pr_info("%s: Test OK\n", name);
302         return 0;
303 bailout:
304         sdahi(adap);
305         sclhi(adap);
306         return -ENODEV;
307 }
308
309 /* ----- Utility functions
310  */
311
312 /* try_address tries to contact a chip for a number of
313  * times before it gives up.
314  * return values:
315  * 1 chip answered
316  * 0 chip did not answer
317  * -x transmission error
318  */
319 static int try_address(struct i2c_adapter *i2c_adap,
320                        unsigned char addr, int retries)
321 {
322         struct i2c_algo_bit_data *adap = i2c_adap->algo_data;
323         int i, ret = 0;
324
325         for (i = 0; i <= retries; i++) {
326                 ret = i2c_outb(i2c_adap, addr);
327                 if (ret == 1 || i == retries)
328                         break;
329                 bit_dbg(3, &i2c_adap->dev, "emitting stop condition\n");
330                 i2c_stop(adap);
331                 udelay(adap->udelay);
332                 yield();
333                 bit_dbg(3, &i2c_adap->dev, "emitting start condition\n");
334                 i2c_start(adap);
335         }
336         if (i && ret)
337                 bit_dbg(1, &i2c_adap->dev, "Used %d tries to %s client at "
338                         "0x%02x: %s\n", i + 1,
339                         addr & 1 ? "read from" : "write to", addr >> 1,
340                         ret == 1 ? "success" : "failed, timeout?");
341         return ret;
342 }
343
344 static int sendbytes(struct i2c_adapter *i2c_adap, struct i2c_msg *msg)
345 {
346         const unsigned char *temp = msg->buf;
347         int count = msg->len;
348         unsigned short nak_ok = msg->flags & I2C_M_IGNORE_NAK;
349         int retval;
350         int wrcount = 0;
351
352         while (count > 0) {
353                 retval = i2c_outb(i2c_adap, *temp);
354
355                 /* OK/ACK; or ignored NAK */
356                 if ((retval > 0) || (nak_ok && (retval == 0))) {
357                         count--;
358                         temp++;
359                         wrcount++;
360
361                 /* A slave NAKing the master means the slave didn't like
362                  * something about the data it saw.  For example, maybe
363                  * the SMBus PEC was wrong.
364                  */
365                 } else if (retval == 0) {
366                         dev_err(&i2c_adap->dev, "sendbytes: NAK bailout.\n");
367                         return -EIO;
368
369                 /* Timeout; or (someday) lost arbitration
370                  *
371                  * FIXME Lost ARB implies retrying the transaction from
372                  * the first message, after the "winning" master issues
373                  * its STOP.  As a rule, upper layer code has no reason
374                  * to know or care about this ... it is *NOT* an error.
375                  */
376                 } else {
377                         dev_err(&i2c_adap->dev, "sendbytes: error %d\n",
378                                         retval);
379                         return retval;
380                 }
381         }
382         return wrcount;
383 }
384
385 static int acknak(struct i2c_adapter *i2c_adap, int is_ack)
386 {
387         struct i2c_algo_bit_data *adap = i2c_adap->algo_data;
388
389         /* assert: sda is high */
390         if (is_ack)             /* send ack */
391                 setsda(adap, 0);
392         udelay((adap->udelay + 1) / 2);
393         if (sclhi(adap) < 0) {  /* timeout */
394                 dev_err(&i2c_adap->dev, "readbytes: ack/nak timeout\n");
395                 return -ETIMEDOUT;
396         }
397         scllo(adap);
398         return 0;
399 }
400
401 static int readbytes(struct i2c_adapter *i2c_adap, struct i2c_msg *msg)
402 {
403         int inval;
404         int rdcount = 0;        /* counts bytes read */
405         unsigned char *temp = msg->buf;
406         int count = msg->len;
407         const unsigned flags = msg->flags;
408
409         while (count > 0) {
410                 inval = i2c_inb(i2c_adap);
411                 if (inval >= 0) {
412                         *temp = inval;
413                         rdcount++;
414                 } else {   /* read timed out */
415                         break;
416                 }
417
418                 temp++;
419                 count--;
420
421                 /* Some SMBus transactions require that we receive the
422                    transaction length as the first read byte. */
423                 if (rdcount == 1 && (flags & I2C_M_RECV_LEN)) {
424                         if (inval <= 0 || inval > I2C_SMBUS_BLOCK_MAX) {
425                                 if (!(flags & I2C_M_NO_RD_ACK))
426                                         acknak(i2c_adap, 0);
427                                 dev_err(&i2c_adap->dev, "readbytes: invalid "
428                                         "block length (%d)\n", inval);
429                                 return -EREMOTEIO;
430                         }
431                         /* The original count value accounts for the extra
432                            bytes, that is, either 1 for a regular transaction,
433                            or 2 for a PEC transaction. */
434                         count += inval;
435                         msg->len += inval;
436                 }
437
438                 bit_dbg(2, &i2c_adap->dev, "readbytes: 0x%02x %s\n",
439                         inval,
440                         (flags & I2C_M_NO_RD_ACK)
441                                 ? "(no ack/nak)"
442                                 : (count ? "A" : "NA"));
443
444                 if (!(flags & I2C_M_NO_RD_ACK)) {
445                         inval = acknak(i2c_adap, count);
446                         if (inval < 0)
447                                 return inval;
448                 }
449         }
450         return rdcount;
451 }
452
453 /* doAddress initiates the transfer by generating the start condition (in
454  * try_address) and transmits the address in the necessary format to handle
455  * reads, writes as well as 10bit-addresses.
456  * returns:
457  *  0 everything went okay, the chip ack'ed, or IGNORE_NAK flag was set
458  * -x an error occurred (like: -EREMOTEIO if the device did not answer, or
459  *      -ETIMEDOUT, for example if the lines are stuck...)
460  */
461 static int bit_doAddress(struct i2c_adapter *i2c_adap, struct i2c_msg *msg)
462 {
463         unsigned short flags = msg->flags;
464         unsigned short nak_ok = msg->flags & I2C_M_IGNORE_NAK;
465         struct i2c_algo_bit_data *adap = i2c_adap->algo_data;
466
467         unsigned char addr;
468         int ret, retries;
469
470         retries = nak_ok ? 0 : i2c_adap->retries;
471
472         if (flags & I2C_M_TEN) {
473                 /* a ten bit address */
474                 addr = 0xf0 | ((msg->addr >> 7) & 0x03);
475                 bit_dbg(2, &i2c_adap->dev, "addr0: %d\n", addr);
476                 /* try extended address code...*/
477                 ret = try_address(i2c_adap, addr, retries);
478                 if ((ret != 1) && !nak_ok)  {
479                         dev_err(&i2c_adap->dev,
480                                 "died at extended address code\n");
481                         return -EREMOTEIO;
482                 }
483                 /* the remaining 8 bit address */
484                 ret = i2c_outb(i2c_adap, msg->addr & 0x7f);
485                 if ((ret != 1) && !nak_ok) {
486                         /* the chip did not ack / xmission error occurred */
487                         dev_err(&i2c_adap->dev, "died at 2nd address code\n");
488                         return -EREMOTEIO;
489                 }
490                 if (flags & I2C_M_RD) {
491                         bit_dbg(3, &i2c_adap->dev, "emitting repeated "
492                                 "start condition\n");
493                         i2c_repstart(adap);
494                         /* okay, now switch into reading mode */
495                         addr |= 0x01;
496                         ret = try_address(i2c_adap, addr, retries);
497                         if ((ret != 1) && !nak_ok) {
498                                 dev_err(&i2c_adap->dev,
499                                         "died at repeated address code\n");
500                                 return -EREMOTEIO;
501                         }
502                 }
503         } else {                /* normal 7bit address  */
504                 addr = msg->addr << 1;
505                 if (flags & I2C_M_RD)
506                         addr |= 1;
507                 if (flags & I2C_M_REV_DIR_ADDR)
508                         addr ^= 1;
509                 ret = try_address(i2c_adap, addr, retries);
510                 if ((ret != 1) && !nak_ok)
511                         return -ENXIO;
512         }
513
514         return 0;
515 }
516
517 static int bit_xfer(struct i2c_adapter *i2c_adap,
518                     struct i2c_msg msgs[], int num)
519 {
520         struct i2c_msg *pmsg;
521         struct i2c_algo_bit_data *adap = i2c_adap->algo_data;
522         int i, ret;
523         unsigned short nak_ok;
524
525         bit_dbg(3, &i2c_adap->dev, "emitting start condition\n");
526         i2c_start(adap);
527         for (i = 0; i < num; i++) {
528                 pmsg = &msgs[i];
529                 nak_ok = pmsg->flags & I2C_M_IGNORE_NAK;
530                 if (!(pmsg->flags & I2C_M_NOSTART)) {
531                         if (i) {
532                                 bit_dbg(3, &i2c_adap->dev, "emitting "
533                                         "repeated start condition\n");
534                                 i2c_repstart(adap);
535                         }
536                         ret = bit_doAddress(i2c_adap, pmsg);
537                         if ((ret != 0) && !nak_ok) {
538                                 bit_dbg(1, &i2c_adap->dev, "NAK from "
539                                         "device addr 0x%02x msg #%d\n",
540                                         msgs[i].addr, i);
541                                 goto bailout;
542                         }
543                 }
544                 if (pmsg->flags & I2C_M_RD) {
545                         /* read bytes into buffer*/
546                         ret = readbytes(i2c_adap, pmsg);
547                         if (ret >= 1)
548                                 bit_dbg(2, &i2c_adap->dev, "read %d byte%s\n",
549                                         ret, ret == 1 ? "" : "s");
550                         if (ret < pmsg->len) {
551                                 if (ret >= 0)
552                                         ret = -EREMOTEIO;
553                                 goto bailout;
554                         }
555                 } else {
556                         /* write bytes from buffer */
557                         ret = sendbytes(i2c_adap, pmsg);
558                         if (ret >= 1)
559                                 bit_dbg(2, &i2c_adap->dev, "wrote %d byte%s\n",
560                                         ret, ret == 1 ? "" : "s");
561                         if (ret < pmsg->len) {
562                                 if (ret >= 0)
563                                         ret = -EREMOTEIO;
564                                 goto bailout;
565                         }
566                 }
567         }
568         ret = i;
569
570 bailout:
571         bit_dbg(3, &i2c_adap->dev, "emitting stop condition\n");
572         i2c_stop(adap);
573         return ret;
574 }
575
576 static u32 bit_func(struct i2c_adapter *adap)
577 {
578         return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL |
579                I2C_FUNC_SMBUS_READ_BLOCK_DATA |
580                I2C_FUNC_SMBUS_BLOCK_PROC_CALL |
581                I2C_FUNC_10BIT_ADDR | I2C_FUNC_PROTOCOL_MANGLING;
582 }
583
584
585 /* -----exported algorithm data: -------------------------------------  */
586
587 static const struct i2c_algorithm i2c_bit_algo = {
588         .master_xfer    = bit_xfer,
589         .functionality  = bit_func,
590 };
591
592 /*
593  * registering functions to load algorithms at runtime
594  */
595 static int i2c_bit_prepare_bus(struct i2c_adapter *adap)
596 {
597         struct i2c_algo_bit_data *bit_adap = adap->algo_data;
598
599         if (bit_test) {
600                 int ret = test_bus(bit_adap, adap->name);
601                 if (ret < 0)
602                         return -ENODEV;
603         }
604
605         /* register new adapter to i2c module... */
606         adap->algo = &i2c_bit_algo;
607         adap->retries = 3;
608
609         return 0;
610 }
611
612 int i2c_bit_add_bus(struct i2c_adapter *adap)
613 {
614         int err;
615
616         err = i2c_bit_prepare_bus(adap);
617         if (err)
618                 return err;
619
620         return i2c_add_adapter(adap);
621 }
622 EXPORT_SYMBOL(i2c_bit_add_bus);
623
624 int i2c_bit_add_numbered_bus(struct i2c_adapter *adap)
625 {
626         int err;
627
628         err = i2c_bit_prepare_bus(adap);
629         if (err)
630                 return err;
631
632         return i2c_add_numbered_adapter(adap);
633 }
634 EXPORT_SYMBOL(i2c_bit_add_numbered_bus);
635
636 MODULE_AUTHOR("Simon G. Vogl <simon@tk.uni-linz.ac.at>");
637 MODULE_DESCRIPTION("I2C-Bus bit-banging algorithm");
638 MODULE_LICENSE("GPL");